Abraham Maslow proposed a hierarchy of needs consisting of physiological needs, safety needs, love needs, esteem needs, and self-actualization needs. He believed humans are motivated to fulfill lower level needs before progressing to higher level needs, starting with basic physiological needs and moving up to needs for love, esteem, and self-fulfillment. The hierarchy suggests humans are motivated to fulfill unsatisfied needs and will address higher level needs like belongingness and esteem only once lower level needs are satisfied.